The present invention generally relates to telecommunication techniques. More particularly, the present invention relates to a method for providing a scheme in which groups of users are able to share communication resources (e.g., time-frequency resource) in a wireless communication network. More specifically, embodiments of the present invention allows wireless communication network users who are assigned to one or more groups to access and use the wireless communication network for various types of communications in an efficient manner by sharing communication channels. For example, valuable resources that are not utilized for voice communication are used for transferring data. But it would be recognized that the invention has a much broader range of applicability.
While packet data traffic and applications thereof have been rapid developed and widely utilized, quality voice transmission remains a fundamental aspect of designing a wireless communication system. Efficient management of coexisting voice and data users is often essential to the network performance, especially in a wireless communication network. For example, in a CDMA2000 1x EVolution Data Optimized (1xEV-DO) system, transmissions of packet data and voice over IP (VoIP) traffics between Access Network (AN) and Access Terminal (AT) are typically scheduled by the AN.
Voice traffic, while being a part of a real time application, is usually discontinuous in nature and composes of large inactive periods. It is often desired to group a certain number of voice users together and assign them a set of shared time-frequency resource. The statistical multiplexing gain is achieved among the group members. For example, when the base station has determined a discontinuous transmission (DTX) state for a user in a particular time period, it can assign the user's transmission (e.g., time and/or frequency) resources to another user. The statistical multiplexing gain is also achieved through the early terminated hybrid automatic request (HARQ) transmissions. For example, once a user acknowledges its VoIP packet, the time-frequency resources become available to other group members based on the implemented scheduling algorithm.
Over the past, various conventional techniques have been proposed to allow unused transmission resource to be allocated to other users for voice communication. For example, such technique has been proposed in the Third Generation Partnership Project 2 (3GPP2).
According to a conventional technique, a unique identifier (e.g., GroupID) is assigned to a group when the group is established. When access node (AN) assigns an access terminal (AT) to the group, the AN associates the AT's unique identifier (e.g., MACIndex) to the GroupID through a Group Setup Message, as shown in Table 1. The message is managed through upper layer signaling carried on Forward Link Data Channel (F-DCH).
TABLE 1Group Setup Message for Voice UsersFieldDescriptionMAC_IndexUnique identifier of the ATGroup_IDUnique identifier for the groupBlock_SizeThe fundamental block size (e.g. 1 DRCH by1 Frame)Num_BlocksNumber of blocks assigned to this groupFirst_BlockAddress of the first block in the assignmentOrdering_PatternOne of a few choices indicating theorder in which the blocks are to be distributedF_Mod_CodingCoding and modulation for full rate framesH_Mod_CodingCoding and modulation for half rate framesQ_Mod_CodingCoding and modulation for quarter rate framesE_Mod_CodingCoding and modulation for eighth rate framesInterlace_StructureThe pattern and structure of the VoIP interlaceBitmap1_LengthLength of the first bitmapBitmap2_LengthLength of the second bitmap (if used)Bitmap_ChannelTime frequency resources for the bitmap itselfAT_IndexThe bitmap position assigned to the ATInterlace_OffsetOffset assigned to the AT indicative of itsfirst transmission
The Group Setup Message defines the exact locations of the resource blocks and an ordering pattern indicative of the order in which the resources are allocated. In the time domain, the set of shared resources is a group of VoIP frames comprising a VoIP interlace pattern. In the frequency domain, the shared resource is typically a set of DRCHs (Distributed Resource Channel), although a set of BRCHs (Block Resource Channel) could be used also.
Each AT is assigned a unique ordering index within the group, and a fixed interlace offset within a superframe for its first subpacket transmission. This is to align the time between successive first transmissions to the vocoder frame duration (e.g., approximately 20 msec).
Once a group of users is established and assigned a set of shared time-frequency resources, Group Resource Allocation message that uses bitmap signaling is utilized to assign resource to individual users in each VoIP frame. FIG. 1 is a simplified diagram illustrating a conventional resource allocation technique. The bitmap signaling is used by the base station to assign resources and by the users to determine their exact resources within the set of shared time-frequency resources. It is used for first subpacket and subsequent retransmissions.
A first bitmap (e.g., referred to as bitmap1) has a length of number of users in the group. This first bitmap is used to indicate which ATs are being served in each VoIP frame, where each AT corresponds to a fixed location in the bitmap based on its ordering index. For example, the “1” indicates an active user and a “0” indicates a non-active user in the corresponding VoIP frame. A second bitmap (e.g., referred to as bitmap2) may be used to indicate the amount of resources (e.g., number of assigned blocks and/or the packet format) allocated to the corresponding user.
Each AT determines its allocation based on the allocations for all ATs with a smaller bitmap position in the first bitmap. The first bitmap is used to indicate active ATs. The bitmap locations correspond to the AT positions. For example, the AT assigned the 0th group position determines its assignment based on the 0th position in the first bitmap. Each AT with a “1” in the first bitmap is active. For example, the AT with the first ‘1’ is assigned the first M blocks, and the AT with the second “1” is assigned the second N blocks, and so on. The M and N are the same if only the first bitmap is available, and M and N may be different if there are two bitmaps. The user with the first “1” in the first bitmap corresponds to the first position in the second bitmap, the user with the second “1” in the first bitmap corresponds to the second position in the second bitmap, etc. According to certain embodiments, the users with “0” in the first bitmap also have a position in the second bitmap.
The ATs are assigned an ACK position based on their position assignment in the first bitmap. For example, the first N/2 ATs in the first bitmap will be assigned to transmit their ACK in the first ACK position, while the second N/2 ATs in the first bitmap will be assigned to transmit their ACK in the second ACK position. Similarly, an even/odd structure could be used, whereby ATs with an odd position assignment in the first bitmap will be assigned to transmit their ACK in the first ACK position, while ATs with an even position assignment in the first bitmap will be assigned to transmit their ACK in the second ACK position.
To minimize the impact of a detection error of a new H-ARQ sequence indicator, the beginning of a new H-ARQ sequence is indicated by an ARQ Instance Sequence Number (AI_SN) that toggles between two indicators when the transmission for a new H-ARQ sequence starts and the signal remains the same when the transmission is for the subsequent sub-packet of a previously failed sub-packet. Specifically, a transmitter transmits the same indicator with each sub-packet of the same H-ARQ sequence. With the beginning of a new H-ARQ sequence, the transmitter switches the indicator to the other indicator. If a receiver misses the new H-ARQ indicator with the first sub-packet transmission, the receiver can still detect the new H-ARQ indicator because the indicator in the subsequent sub-packet transmission is different from the indicator used in the previous packet transmission. Therefore, the new H-ARQ indicator is sufficiently robust to detection error.
The method as described above is useful for many applications. Unfortunately, this method, along with other conventional techniques, may not be adequate for various reasons. Therefore, an improved system and method is desired.